The Heckler & Koch HK45 is a semi-automatic handgun created to satisfy the requirements of the U.S. Military Joint Combat Weapon program, which aimed to equip the U.S. Military with a .45 ACP semi-automatic pistol rather than the 9mm M9 pistol. The HK45 is an evolutionary improvement of the Heckler & Koch USP and shares the same operating characteristics as that handgun. Heckler & Koch worked hard to make the HK45, a full-size model handgun, more ergonomic than the HK USP full-size pistol chambered in.45 ACP by adding elements from the P2000, like an expanded ambidextrous slide release, a comfortable textured grip with finger grooves, and replaceable backstraps to accommodate hands of different sizes. The HK45 features and 4.46-inch barrel and a 10-magazine capacity to fit the smaller, more ergonomic grip. By utilizing HK's special internal mechanical recoil reduction system, the recoil forces delivered to the gun and shooter may be reduced by 30%, optimizing shooter control during rapid shooting and prolonging component service life. The HK45, which is ideal for personal defense use, is available in a broad number of variants that employ various trigger firing modes, including SA/DA or DAO. Variants: the HK45 Compact (a shortened barrel of 3.94 inches); the HK45 Tactical and HK45 Compact Tactical ( with an extended threaded barrel for suppressors, 4.57 and 5.2 inches, and tritium front and rear sights).